Kangaroo Rats Pocket Mice and Kangaroo Mice: Heteromyidae

Physical characteristics: San Joaquin (san-wah-KEEN) pocket mice are small sand-colored mice with soft coats, sparse darker back hairs, and yellowish undersides. They do not have spiny hairs that are often found on other pocket mice species. A line separates the lighter belly hairs from the darker back hairs. San Joaquin pocket mice have short ears that sometimes have a base patch of lighter hair. Their hind feet have hair on the soles and their long tails are covered with hair with a small hair tuft on tip. They have external fur-lined cheek patches that are used for storing and transporting food. Adults are 5.0 to 6.3 inches (13 to 16 centimeters) long and weigh between 0.22 and 0.39 ounces (7 and 12 grams).

Geographic range: They are found in west-central California.

San Joaquin pocket mice not only eat seeds, but help to scatter them, which helps to maintain a healthy environment. (Illustration by Michelle Meneghini. Reproduced by permission.)

Habitat: San Joaquin pocket mice inhabit arid grasslands, deserts, and scrublands, especially areas with fine soils.

Diet: Their diet consists of seeds of grasses, shrubs, and forbs, broad-leaved herbaceous plants that grow in prairies and meadows. San Joaquin pocket mice forage, search for food, within shrub branches. They also eat soft-bodied insects such as cutworms and grasshoppers, and rarely drink water, getting almost all moisture through their food.

Behavior and reproduction: San Joaquin pocket mice do not travel far to forage, and stay away from open areas. They bathe by rubbing their sides and ventrum, external opening by which wastes pass in primitive mammals, in the sand. Their breeding season is from March to July. Females have at least two litters of four to six babies per litter.

San Joaquin pocket mice and people: San Joaquin pocket mice help to scatter seeds, which helps to maintain a healthy environment where it lives.

Conservation status: San Joaquin pocket mice are listed by the U.S. Fish and Wildlife Service as a species of special concern. Two subspecies, populations of a species in a specific area, are listed as Near Threatened. ∎